Sofa



FIG. 1 is a front perspective view of a sofa showing my new design;

FIG. 2 is an end perspective view thereof taken from the left of FIG. 1, the end perspective view thereof taken from the right of FIG. 1 being the mirror image thereof;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a rear perspective view thereof. 

The ornamental design for a sofa, as shown and described. 